Value of Conventional MRI, DCE-MRI, and DWI-MRI in the Discrimination of Metastatic from Non-Metastatic Lymph Nodes in Rectal Cancer: A Systematic Review and Meta-Analysis Study

BACKGROUND: Today, despite many studies on the diagnosis of metastasis to lymph nodes (LNs) in Rectal Cancer (RC), its diagnosis is still very challenging for radiologists. The purpose of the present study was to the assessment of the diagnostic value of conventional MRI, DCE-MRI, and DWI-MRI in the discrimination of metastatic from non-metastatic lymph nodes in RC. METHODS: In the present meta-analysis study, we surveyed international databases including PubMed, Scopus, Embase, and Science Direct with appropriate keywords. Using the binomial distribution formula, the variance of each study was calculated and the data were analyzed using STATA version 14. Finally, the results of the studies were entered into the random-effects meta-analysis. Also, we used the chi-squared test and I2 index to calculate heterogeneity among studies, and for evaluating publication bias, Funnel plots and Egger tests were used. RESULTS: 31 articles published between 2005 and 2021, comprising 2517 patients were included in the present study. The sensitivity and specificity of DCE-MRI were 83% (74% to 80%), and 86% (80% to 93%), respectively with PPV 84% (76% to 89%) and NPV 88% (79% to 95%). Also, the sensitivity and specificity of DWI-MRI were 81% (74% to 88%), and 74% (78% to 91%), respectively with PPV 63% (54% to 74%), NPV 85% (77% to 93%), AUC 80 % (75% to 86%) and accuracy 82% (75% to 88%). For conventional MRI, the sensitivity 74% (67% to 80%), specificity 77% (71% to 83%), PPV 62% (48% to 69%), NPV 70% (62% to 77%), AUC 78% (72% to 83%) and 71% accuracy (68% to 78%) was obtained. CONCLUSION: Based on our finding DCE-MRI is the most suitable technique for the discrimination of metastatic lymph nodes in rectal cancer.